Condensed Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net income	$ 133,177	$ 133,323
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	65,435	63,073
Loss on disposal of property and equipment	78	477
Share-based compensation	2,073	1,933
Other operating activities, net	3,255	7,369
Net cash provided by operating activities	204,018	206,175
Cash flows from investing activities:
Purchase of property and equipment	(52,211)	(70,741)
Proceeds from sale of property and equipment	1,543	277
Net cash used in investing activities	(50,668)	(70,464)
Cash flows from financing activities:
Payments for share repurchases	(178,294)	(30,596)
Dividends paid	(18,310)	(13,790)
Other financing activities, net	(3,345)	(980)
Net cash used in financing activities	(199,949)	(45,366)
(Decrease) Increase in cash and cash equivalents	(46,599)	90,345
Cash and cash equivalents at beginning of period	403,571	190,282
Cash and cash equivalents at end of period	$ 356,972	$ 280,627